Gaseous-discharge apparatus



June 4, 1957 H. E. EDGERTON 2,794,906

' GASEOUS -DISCHARGE APPARATUS Filed June 16, 1954 INVENTOR. flzwzo'fmmrolv BYZ M A T T ORNEYS United States Patent-O F GASEOUS-DISCHARGEAPPARATUS Harold E. Edgerton, Belmont, Mass.

Application June 16, 1954, Serial No. 437,106

19 Claims. (Cl. Mil-41.4)

The present invention relates to electric-discharge apparatus and moreparticularly .to gas-filled tubes in which an electric discharge takesplace between an anode and a cathode associated with the tube.

An important application of gaseous-discharge tube-s is that ofproducing flash illumination for such purposes as flash photography orstroboscopy. Flashtubes of this character generally embody an anode anda cathode disposed within the gas in the tube. When an electricdischarge is produced through the gas in the tube between the anode andthe cathode, a flash of light is emitted through the walls of the tubein the region between the anode and the cathode. This discharge may beinitiated by control of the voltage at the anode and the cathode alone,or, preferably, with the aid of an auxiliary or trigger electrodedisposed between the anode and .the cathode. Such flashtubes haveheretofore been mounted within paraboloidal and similar light-wavereflectors to direct as a beam the illumination produced by the flashesof light from the flashtube. Apparatus of this character is described,for example, in my prior United States Letters Patent No. 2,358,796,issued September 26, 1944, and No. Re. 22,611, issued March 6, 194 5.The fiashtubes therein disclosed are of helical construction disposed inthe reflector with the axis of the helix oriented substantially parallelto or coincident with the axis of the reflector. Helical tubes, however,are not only costly to manufacture, but considerable flash illuminationis wasted in 'view of the fact that some turns of the helical tube arein front of others. In addition, the light emanating from the tube isnot produced only in the region of the focus of the reflector, so thatthe effectiveness of the reflector -as a beam director is impaired. Ithas, however, heretofore been proposed to utilize discharge tubescomprising an envelope in the form of a single loop that may be disposedin the focal region of a reflector. Such devices have been suggested,for example, for use in automobile headlights and other types ofprojector lamps. Such devices,however, are intricate to manufacture andare not particularly suited as highintensity flashtubes ,or for use inflash photography and in stroboscopic applications.

An object of the invention, therefore, is to provide a new and improvedgaseous-discharge device that shall not be subject to any of theabove-mentioned dis-advantages and that is particularly adapted for useas a flashtube with light-wave reflectors of the paraboloidal type. Insummary, the present inventionembodies a flashtube that comprises atubular envelope looped ,into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring. A pair of principal electrodesis mounted within the envelope at the said diverging terminal portionsand a trigger electrode is positioned at .a point of the ring displacedfrom the said predetermined point. An electrical connector is connectedtoeach off the electrodes and is mounted to extend in a directionsubstantially perpendicular to the plane of the 2,794,906 Patented June4, 1957 2v ring toward the reflector. The electrical connectors arereceived within insulated apertures in the reflector to permit of easyattachment and detachment of the flash- ,tube, and to maintain theflashtube rigidly positioned, when attached, and easily connectable tothe flashtube circuit.

A further object is to provide such a flashtube in which theelectrode-connection structures themselves serve to provide rigidmechanical supporting means for positioning the flashtube in the exactdesired location with respect to the reflector.

Still a further object is to provide a new and improved type of mountingfor a gaseous-discharge device.

An additional object is to provide a more efficient and less costlygaseous-discharge device.

Other and further objects will be set forth hereinafter and will be moreparticularly pointed out in the appended claims.

The invention will now be described in connection with the accompanyingdrawings:

Fig. 1 of which is a combined fragmentary perspective and circuitdiagram illustrating a flashtube constructed in accordance with apreferred embodiment of the pres- .ent invention and connected with alight flash-producing system;

Figs. 2 and 3 are, respectively, front and side elevations of theflashtube of Fig. 1;

Fig. 4 is a side elevation of a modified flashtube construction; and

'Fig. 5 is a fragmentary perspective of a further modification.

Referring to Fig. l, the flashtube 1 is shown in the form of a tube ofglass, fused quartz or other light transparent material, looped into asingle ,closed ring, preferably of circular contour. The rightandleft-hand terminal portions 3 and 5 of the ring cross each other atpreferably the lowermost point X of the ring and then ,diverge away fromthe ring at the said lowermost point X. The rightand left-hand ends 7and 9 of the terminal portions 3 and 5 of the envelope 1 are sealed sothat the envelope may contain a gaseous medium of any desired nature,such, for example, as is described in the said Letters Patent. An anodeprincipal electrode 11 is shown disposed within the envelope 1 in theterminal portion 3 near the end 7 thereof, and a principal cathodeelectrode 13 is similarly shown supported near the end 9 of the terminalportion 5. Each of the principal electrodes 11 and 13 is supported ,atpoints within the respective terminal portions 3 and 5 of the flashtube'1 outside the closed ring thereof by rigid conductors 15 and 17 thatextend through the sealed ends 7 and 9 of the terminal portions 3 and 5.The cathodeelectrode 13 may be of the sintered type, such as isdescribed in United States Letters Patent No. 2,492,142 issued December27, 1949, to Kenneth J. Germeshausen, though other types of cathodesmay, of course, also be employed. The anode 11 similarly may be of anydesired conventional type such as, for example, the type described inany of the said Letters Patent,

In accordance with a preferred embodiment of the invention, theconductors 15 and 17 are connected by preferably flexible conductiveextensions 19 and 21 to electrical connectors 23 and 25. The connectors23 and 2 5 are preferably rigid elements, such as jacks, mounted uponbands 27 and 29 that may be disposed about the terminal portions 3 and 5of the envelope' l, preferably at positions between the locations of theprincipal electrodes '11 and 13 and the respective sealed ends 7 and 9.The jacks 23, 25 extend from the bands 27, 29, in the same directionaway from and substantially perpendicular to the plane of the ring ofthe envelope 1, shown to the left in Figs. 1 and 3.

The light-wave reflector 2, which is preferably of substantiallyparaboloidal shape, is provided with apertures 31 that may containinsulating gaskets 33, as of rubber or similar material, for receivingthe terminal portions of the jack connectors 23 and 25. In Fig. 1, forexample, the terminal portion 35 of the jack connector 25 is shownreceived within the apertured gasket 33. A collar 37 upon the jack 25serves to limit the degree of insertion of the terminal portion 35 ofthe jack 25 within the apertured gasket 33, thus controlling thedistance of the terminal portion of the flashtube 1 from the reflector2. The jack 23 associated with the other terminal portion 3 of theflashtube 1 is similarly inserted within a similar gasket 33 at anotherpoint in the reflector 2.

In the case of three-electrode flashtubes, above mentioned, that areprovided with a third or trigger electrode of any desired type, such asthe external band electrode 39 disposed at a point substantiallydiametrically opposite to the point X of the ring of the envelope 1, thetrigger electrode itself may serve as a mechanical supporting structurefor a third electrical connector jack 41. The connector 41 may besimilar in all respects to the jack connectors 23 and 25, beforedescribed, and may be received in a similar apertured gasket 33 at athird point in the reflector. In order to provide optimum mechanicalrigidity to such a three-point suspension as is 7 established by theconnectors 23, 25 and 41 of the flashtube 1, it is preferable thatimaginary lines joining the three connectors 23, 25 and 41 and thecorresponding apertured gaskets 33 of the reflector 2 be disposed at thevertices of a substantially equilateral triangle, having an angle of 60degrees, as shown in dashed lines in Fig. 2. As before stated, the useof the collars on the jack connectors, such as the collar 37 of the jack25, and connectors of appropriate lengths, permit exact locating of theflashtube 1 in the focal plane, or in any other desired position, withrespect to the concave side of the reflector 2. The tube 1 may thus beeasily attached or mounted upon the reflector 2 with the assurance thatthe tube 1 is always place-i at the exact desired location and isrigidly mounted upon the reflector 2, without the necessity for fineadjustments.

Electric connections between the connector jacks and the desiredflash-producing circuit may be provided on the convex side of thereflector 2. In Fig. 1, for example, a flash condenser or capacitor 4may be connected by a wire conductor 6 to the end of the terminalportion 35 of the jack connector 25, as by a solder connection at thejoint 8. Where a temporary and not a permanent connection is desired,the conductor 6, on the other hand, may be provided with a female typeof connector 26, Fig. 5, for receiving the terminal portion 35 of thejack 25. Other types of electric-connector devices may similarly beemployed. The lower terminal of the capacitor 4 is connected by aconductor 10 to the terminal portion of the jack 23. The flash condenseror capacitor 4 receives its voltage from any desired source of energy,such as a battery 12, that may be connected to charge the flashcondenser 4 through a charging impedance 14 upon the closure of a powerswitch S. The voltage accumulated upon the charged capacitor 4 istherefore applied by the conductors 6 and 10, the respective jacks 25and 23, and the respective conductors 21-17 and 19-15 to the respectiveprincipal electrodes 13 and 11 of the flashtube 1. The voltage to whichthe condenser 4 is charged from the source 12, however, is preferablynot of itself high enough to permit a discharge to take place in thegaseous medium of the envelope 1 between the cathode 13 and the anode11. It is preferably necessary, to the contrary, to utilize the triggerelectrode 39 to break down the gaseous medium in order that thecondenser 4 may thereupon discharge its voltage between the cathode 13and the anode 11 through the ring of the tube 1, thereby to produce aflash of light. This triggering may be eflected with the aid of astep-up triggering transformer 16, the upper terminal of the secondarywinding 18 of which is connected by a conductor 20 to the jack 41, andthus to the trigger electrode 39. The lower terminal of the secondarywinding 18 may be connected to the conductor 6. Any desired triggerdevice 22 may apply a voltage impulse in the primary winding 24 of thetrigger transformer 16 in order to induce in the secondary winding 18 atriggering impulse that is applied by the conductors 20 and 6 betweenthe trigger electrode 39 and the cathode 13 of the flashtube 1, therebyto initiate the discharge of the condenser 4 between the cathode 13 andthe anode 11. The triggering device 22 may be of any well-known type,including mechanical switching devices or electronic triggering circuitsas disclosed, for example, in the before-mentioned Letters Patent. Anyother type of flash-producing circuit may similarly be employed with thetube of the present invention.

In addition to providing for the accurate, rigid and simple mechanicalpositioning of the tube 1 with respect to the reflector 2, and forconvenient electrical connections thereto, the present invention reducesmaterially the cost of manufacture of flashtubes. This is because it ismerely necessary to loop the heated tubular material of the envelopeinto a single convolution or ring of any desired dimensions, includingvery small-sized rings, with the terminal portions crossing, to seal theprincipal electrodes and the gas within the tube, and then to utilizesimple external mounting devices with jack or other connectors which caneasily and inexpensively be mounted external to the envelope 1. Thesimplified tube construction and the attachment and detachment featuresof the present invention, moreover, render the same particularly usefulin portable flash-photography apparatus where limited weight and sizerequirements are imposed and where it is also important that theoperator be able to replace flashtubes rapidly without carefuladjustments.

If desired, the crossing of the terminal portions of the envelope 1 atpoint X may be effected in the manner illustrated in Figs. 1 to 3, withthe terminal portions 3 and 5 slightly diverging, also, out of the planeof the ring, as more particularly shown in Fig. 3. The cross-over, onthe other hand, may be effected as in Fig. 4 with, for

. example, the terminal portion 3 lying substantially in the plane ofthe ring and the terminal portion 5 extending to one side of the saidplane, to the right, as shown in Fig. 4. Further modifications willoccur to those skilled in the art and all such are considered to fallwithin the spirit and scope of the invention as defined in the appendedclaims.

What is claimed is:

1. An electric-discharge device having, in combination,

- a tubular gas-filled envelope looped into a single closed ring withthe terminal portions crossing at a predetermined point along the ringand diverging from the said point away from the ring, and a pair ofelectrodes mounted within the envelope at the said diverging terminalportions.

2. An electric-discharge device having, in combination, a tubulargas-filled envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, a pair of electrodes mountedwithin the envelope at the said diverging terminal portions, and anelectrical connector connected to each of tions, and a third electrodepositioned at a point of the ring displaced from the said predeterminedpoint.

4. An electric-discharge device having, in combination, a tubulargas-filled envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, a pair of electrodes mountedwithin the envelope at the said diverging terminal portions, a thirdelectrode positioned at a point of the ring displaced from the saidpredetermined point, and an electrical connector connected to each ofthe electrodes and mounted to extend in the same direction away from andsubstantially perpendicular to the plane of the ring.

5. An electric-discharge device having, in combination, a tubulargas-filled envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, a pair of electrodes mountedwithin the envelope at the said diverging terminal portions, a thirdelectrode positioned at a point on the ring disposed substantiallyopposite to the said predetermined point, and an electrical connectorconnected to each of the electrodes and mounted to extend in the samedirection away from and substantially perpendicular to the plane of thering, the electrical connectors forming the vertices of a substantiallyequilateral triangle.

6. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed ring with the terminal portionscrossing at a predetermined point along the ring and diverging from thesaid point away from the ring, the envelope being sealed at the ends ofthe terminal portions and containing a gaseous medium, and a pair ofelectrodes mounted within the gaseous medium at the said divergingterminal portions of the envelope and provided with conductors extendingthrough the said sealed ends outside the envelope.

7. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed ring with the terminal portionscrossing at a predetermined point along the ring and diverging from thesaid point away from the ring, the envelope being sealed at the ends ofthe terminal portions and containing a gaseous medium, a pair ofelectrodes mounted within the gaseous medium at the said divergingterminal portions of the envelope and provided with conductors extendingthrough the said sealed ends outside the envelope, and an electricalconnector connected to each of the said conductors outside the envelopeand mounted to extend in the same direction away from and substantiallyperpendicular to the plane of the ring.

8. A flashtube having, in combination, alight-transparent tubularenvelope looped into a single closed ring with the terminal portionscrossing at a predetermined point along the ring and diverging from thesaid point away from the ring, the envelope being sealed at the ends ofthe terminal portions and containing a gaseous medium, apair ofelectrodes mounted within the gaseous medium at the said divergingterminal portions of the envelope and provided with conductors extendingthrough the said sealed ends outside the envelope, a third electrodepositioned at a point of the ring displaced from the said predeterminedpoint, and an electrical connector con nected outside the envelope toeach of the said conductors and to the third electrode and mounted toextend in the same direction away from and substantially perpendicularto the plane of the ring.

9. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed substantially circular ring withthe terminal portions crossing at a predetermined point along the ringand diverging from the said point away from the ring, the envelope beingsealed at the ends of the terminal portions and containing a gaseousmedium, a pair of electrodes constituting an anode and a cathode mountedwithin the gaseous medium at the said diverging terminal portions of theenvelope and provided with conductors extending through the said sealedends outside the envelope, a trigger electrode disposed outside theenvelope at a point of the ring disposed substantially diametricallyopposite to the said predetermined point, and an electrical connectorconnected outside the envelope to each of the said conductors and to thetrigger electrode and mounted to extend in the same direction away fromand substantially perpendicular to the plane of the ring, the electricalconnectors forming the vertices of a substantially equilateral triangle.

10. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed substantially circular ring withthe terminal portions crossing at a predetermined point along the ringand diverging from the said point away from the ring, the envelope beingsealed at the ends of the terminal portions and containing a gaseousmedium, a pair of electrodes constituting an anode and a cathode mountedwithin the gaseous medium at the said diverging terminal portions of theenvelope and provided with conductors extending through the said sealedends outside the envelope, a trigger electrode disposed outside theenvelope at a point of the ring disposed substantially diametricallyopposite to the said predetermined point, bands mounted about the outside of the said terminal portions and connected with the saidconductors, and an electrical jack connector having a limiting flangeconnected to and mounted upon each of the bands and the triggerelectrode and extending in the same direction away from andsubstantially perpendicular to the plane of the ring, the electricalconnectors forming the vertices of a substantially equilateral triangle.

11. A flashtube as claimed in claim 8 and in which the said terminalportions diverge, also, from the said plane of the ring.

12. A flashtube as claimed in claim 8' and in which one of the saidterminal portions lies substantially in the said plane of the ring andthe other terminal portion extends to one side of the said plane.

13. Flashtube apparatus having, in combination, a substantiallyparaboloidal reflector provided with three insulated apertures disposedsubstantially at the vertices of an equilateral triangle surrounding thevertex of the reflector; a flashtube comprising a light-transparenttubular envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, the envelope being sealed at theends of the terminal portions and containing a gaseous medium, a pair ofelectrodes constituting an anode and a cathode mounted within thegaseous medium at the said diverging terminal por tions of the envelopeand provided with conductors extending through the said sealed endsoutside the envelope, a trigger electrode disposed outside the envelopeat a point of the ring disposed substantially opposite to the saidpredetermined point, and an electrical connector connected outside theenvelope to each of the said conductors and to the trigger electrode andmounted to extend in a direction substantially perpendicular to theplane of the ring toward the concave side of the said reflector, theelectrical connectors forming the vertices of substantially the sameequilateral triangle in order that they may be received in the insulatedapertures of the reflector to mount the flashtube substantially in thefocal plane of the reflector; and electrical conductors disposed on theconvex side of the reflector for connecting a source of energy betweenthe two electrical connectors connected to the said anode and cathodeand a trigger circuit to the electrical connector connected to thetrigger electrode, thereby, upon operation of the trigger circuit, topermit the source of energy to produce a flash-discharge in the gaseousmedium around the said ring between the anode and the cathode, theillumination of which is directed into space by the reflector.

14. Electric-discharge apparatus having, in combination, a substantiallyparaboloidal reflector provided with a plurality of apertures; anelectric-discharge device comprising a tubular gas-filled envelopelooped into a single closed ring with the terminal portions crossing ata predetermined point along the ring and diverging from the said pointaway from the ring, a pair of electrodes mounted within the envelope atthe said diverging terminal portions, a third electrode positioned at apoint of the ring displaced from the said predetermined point; and anelectrical connector connected to each of the electrodes and mounted toextend toward the concave side of the reflector, the electricalconnectors being disposed to be received by the reflector apertures inorder to mount the electric-discharge apparatus in substantially thefocal plane of the reflector, electrical connections to theelectricdischarge device being established with the said electricalconnectors at the convex side of the reflector.

15. An electric-discharge device having, in combination, a tubulargas-filled envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, a pair of electrodes mountedwithin the envelope at the said diverging terminal portions, a thirdelectrode positioned at a point on the ring disposed substantiallyopposite to the said predetermined point, and an electrical connectordisposed adjacent to and connected to each of the electrodes and mountedto extend in the same direction away from and substantiallyperpendicular to the plane of the ring, the electrical connectorsforming the vertices of a substantially equilateral triangle.

16. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed substantially circular ring withthe terminal portions crossing at a predetermined point along the ringand diverging from the said point away from the ring, the envelope beingsealed at the ends of the terminal portions and containing a gaseousmedium, a pair of electrodes constituting an anode and a cathode mountedwithin the gaseous medium at the said diverging terminal portions of theenvelope and provided with conductors extending through the said sealedends outside the envelope, a trigger electrode disposed outside theenvelope at a point of the ring disposed substantially diametricallyopposite to the said predetermined point, and an electrical connectoradjacent each electrode and connected outside the envelope to each ofthe said conductors and to the trigger electrode and mounted to extendin the same direction away from and substantially perpendicular to theplane of the ring, the electrical connectors forming the vertices of asubstantially equilateral triangle.

17. A flashtube having, in combination, a light-transparent tubularenvelope looped into a single closed substantially circular ring withthe terminal portions crossing at a predetermined point along the ringand diverging from the said point away from the ring, the envelope beingsealed at the ends of the terminal portions and containing a gaseousmedium, a pair of electrodes constituting an anode and a cathode mountedwithin the gaseous medium at the said diverging terminal portions of theenvelope and provided with conductors extending through the said sealedends outside the envelope, a trigger electrode disposed outside theenvelope at a point of the ring disposed substantially diametricallyopposite to the said predetermined point, bands mounted about theoutside of the said terminal portions adjacent the pair of electrodesand connected with the said conductors, and an electrical jack connectorhaving a limiting flange connected to and mounted upon each of the bandsand the trigger electrode and extending in the same direction away fromand substantially perpendicular to the plane of the ring, the electricalconnectors forming the vertices of a substantially equilateral triangle.

18. Flashtube apparatus having, in combination, a sub stantiallyparaboloidal reflector provided with three insulated apertures disposedsubstantially at the vertices of an equilateral triangle surrounding thevertex of the reflector; a flashtube comprising a light-transparenttubular envelope looped into a single closed ring with the terminalportions crossing at a predetermined point along the ring and divergingfrom the said point away from the ring, the envelope being sealed at theends of the terminal portions and containing a gaseous medium, a pair ofelectrodes constituting an anode and a cathode mounted within thegaseous medium at the said diverging terminal portions of the envelopeand provided with conductors extending through the said sealed endsoutside the envelope, a trigger electrode disposed outside the envelopeat a point of the ring disposed substantially opposite to the saidpredetermined point, and an electrical connector connected outside theenvelope adjacent each electrode and to each of the said conductors andto the trigger electrode and mounted to extend in a directionsubstantially perpendicular to the plane of the ring toward the concaveside of the said reflector, the electrical connectors forming thevertices of substantially the same equilateral triangle in order thatthey may be received in the insulated apertures of the reflector tomount the flashtube substantially in the focal plane of the reflector;and electrical conductors disposed on the convex side of the reflectorfor connecting a source of energy between the two electrical connectorsconnected to the said anode and cathode and a trigger circuit to theelectrical connector connected to the trigger electrode, thereby, uponoperation of the trigger circuit, to permit the source of energy toproduce a flash-discharge in the gaseous medium around the said ringbetween the anode and the cathode, the illumination of which is directedinto space by the reflector.

l9. Electric-discharge apparatus having, in combination, a substantiallyparaboloidal reflector provided with a plurality of apertures; anelectric-discharge device comprising a tubular gas-filled envelopelooped into a single closed ring with the terminal portions crossing ata predetermined point along the ring and diverging from the said pointaway from the ring, a pair of electrodes mounted within the envelope atthe said diverging terminal portions, a third electrode positioned at apoint of the ring displaced from the said predetermined point; and anelectrical connector disposed adjacent to and connected to each of theelectrodes and mounted to extend toward the concave side of thereflector, the electrical connectors being disposed to be received bythe reflector apertures in order to mount the electric-dischargeapparatus in substantially the focal plane of the reflector, electricalconnections to the electric-discharge device being established with thesaid electrical connectors at the convex side of the reflector.

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